A dramatic spike in lawlessness in Libya's two largest cities has edged the country closer to civil war between heavily armed rival militias, stirring concern abroad and on oil markets. Gunmen stormed parliament in southern Tripoli on Sunday, hot on the heels of an anti-Islamist offensive by a rogue general in the eastern city of Benghazi. With interim authorities failing to build a regular army and police force, militias have ruled the roost since they ousted longtime dictator Moamer Kadhafi in a 2011 revolution. After the attack on parliament, a colonel claiming to speak on behalf of the army declared that the General National Congress (GNC) had been suspended. Authorities did not comment but instead called for national dialogue. Justice Minister Salah al-Marghani said two people were killed and 55 wounded in clashes between rival militias in southern Tripoli. But he said the violence had "no real link" to the offensive by ex-general Khalifa Haftar in Benghazi. Witnesses said the Tripoli assailants belonged to the powerful Zintan brigades that have attacked the GNC in the past. MPs were evacuated from the building as heavy gunfire erupted after a convoy of armoured vehicles headed for the GNC. The Zintan brigades control areas in southern Tripoli around the airport. Gunmen set fire to an annex of the parliament building and several cars parked nearby were damaged before the gunmen withdrew towards the airport. Militias have launched several attacks on the GNC, including on March 2 when two lawmakers were shot and wounded. The Tripoli violence came two days after fierce fighting killed 79 people in Benghazi, where Haftar unleashed his so-called National Army on Islamist militiamen, backed by warplanes. Also on Sunday, armed Islamists attacked Benina air base in Benghazi but no one was hurt, its commander Colonel Saad al-Werfalli said. - 'We will return' - Haftar, accused by Tripoli of staging a coup, has said he is readying a new assault on Islamists in Benghazi, vowing to eradicate "terrorism". "Each battle is followed by a regrouping of units. And we will return in force," he said. Haftar, who led ground forces in the 2011 revolution, said: "Our operation is not a coup and we do not plan to seize power." Sharing the Zintan militias' hostility toward the interim parliament, Haftar has said he does not recognise the GNC whose "mandate has already expired and who are rejected by the people". The interim parliament, in which Islamists are strongly represented, sparked outrage earlier this year when it extended its mandate from February until December. Subsequent protests compelled it to promise early elections and a new electoral law. The army says Haftar is backed by tribes, army defectors and former rebels who oppose Libya's interim authorities. His forces on Friday mainly targeted Ansar al-Sharia, designated by the United States as a terrorist group. In the face of growing anarchy in Tripoli, Saudi Arabia on Monday shut down its embassy and evacuated its diplomatic staff on a special flight. Two Tunisian carriers, Tunisair and Syphax Airlines, suspended all flights to and from Libya. Flights resumed later Monday except to Benghazi, where the airport is closed until May 25, Tunisair said. The European Union, meanwhile, said it was "deeply concerned" by the violence in Libya. "The EU renews its commitment to support the Libyan people... and calls on all parties to build consensus so as to ensure a transition to a stable democracy," said foreign affairs head Catherine Ashton's spokesman. With the violence sounding alarm bells abroad, oil prices advanced Monday due to concerns over potential supply disruptions from oil-rich Libya, analysts said. The US benchmark, West Texas Intermediate (WTI) for delivery in June, rose 71 cents to $102.73 a barrel. Brent North Sea crude for delivery in July climbed 41 cents to stand at $110.16 a barrel in London midday deals.